Confidential manuscript submitted to JGR 1 Pitch Angle Dependence of Energetic Electron Precipitation: 2 Energy Deposition, Backscatter, and the Bounce Loss Cone 1 2 3 R. A. Marshall and J. Bortnik 1 4 Ann and H. J. Smead Department of Aerospace Engineering Sciences, University of Colorado Boulder, Boulder, CO 5 80309, USA. 2 6 Department of Atmospheric and Oceanic Sciences, University of California Los Angeles, Los Angeles, CA 90095, USA. 7 Key Points: • 8 We characterize energy deposition and atmospheric backscatter of radiation belt 9 electrons as a function of energy and pitch angle • 10 We use these simulations to characterize the bounce loss cone and show that it is 11 energy dependent • 12 The simulated backscatter of precipitation is characterized by field aligned beams 13 of low energies which should be observable Corresponding author: R. A. Marshall,
[email protected] –1– Confidential manuscript submitted to JGR 14 Abstract 15 Quantifying radiation belt precipitation and its consequent atmospheric effects re- 16 quires an accurate assessment of the pitch angle distribution of precipitating electrons, as 17 well as knowledge of the dependence of the atmospheric deposition on that distribution. 18 Here, Monte Carlo simulations are used to investigate the effects of the incident electron 19 energy and pitch angle on precipitation for bounce-period time scales, and the implica- 20 tions for both the loss from the radiation belts and the deposition in the upper atmosphere. 21 Simulations are conducted at discrete energies and pitch angles to assess the dependence 22 on these parameters of the atmospheric energy deposition profiles and to estimate the 23 backscattered particle distributions.